In addition to a probe over insider trading allegations, hedge fund manager Steven Cohen is embroiled in a dispute with contractors at his new $89 million headquarters.

According to liens filed in Stamford, Conn., Cohen’s hedge fund, SAC Capital, hasn’t paid at least $1.63 million for the gleaming façade on its new home on Stamford’s waterfront. A spokesman for SAC said such liens are a “very normal consequence” of erecting any building, but declined to give any details of the project’s problems.

Cohen opened his headquarters on Cummings Point, in Stamford’s waterfront district, four months ago. The building is a virtual replica of the towering UBS building nearby in downtown Stamford, a small town that’s grown into a stylish base for scores of global corporations.

But SAC – the $3 billion-plus trading firm founded by Cohen, who is described as the world’s most successful and wealthy hedge fund boss – has bigger problems.

The firm has been dragged into an insider trading case involving a high-profile cast of players.

The Securities and Exchange Commission is looking at possible insider trades involving star Lehman Brothers Internet analyst Holly Becker and her husband, Michael Zimmerman, one of SAC’s top portfolio managers.

Another SAC trader, Seth Kanegis, is also involved in certain stock trades being probed by the SEC. Kanegis, 38, is a sometime producer whose films include indie flick “Two Nina,” starring Amada Peet.

Investigators have claimed that Becker’s research reports were somehow hijacked by Zimmerman and used in trading activities at SAC, a firm known for its quick trades.

The SEC is investigating Amazon trades handled at SAC by Kanegis and others.

SAC hasn’t commented on the SEC inquiry, nor have Zimmerman and his wife.

In SAC’s dispute with contractors over its building, one builder said Cohen “is leaving a lot of people waiting for their money.”

“He’s an ornery SOB to do business with,” said the builder, who asked to remain anonymous.

One building industry source said that Cohen “spared no expense” in putting up his headquarters where a former industrial building had stood.

Cohen paid an estimated $60 million for the site, and poured another nearly $30 million into the project.

Three companies that installed the exterior architecture of the SAC headquarters filed liens: Architectural Facades Inc., of Conshocken, Pa.; Linel Signatures of Mooresville, Ind.; and Rainscreens Systems of Emmaus, Pa.

Executives of those three companies didn’t return phone calls.

One insider at SAC said the dispute was over a “performance clause” in its contract.

Some employees at the 100,000-square-foot building said they didn’t see any problems with the building’s interior or its façade.

Another industry source said that the dispute might have arisen from a number of changes that Cohen had ordered during the construction, which ran up the costs of the package.

Tom Conheeney, SAC’s chief operating officer said the dispute wasn’t out of the ordinary.

“Such liens are a very normal consequence of these projects,” he said. “Out of more than 45 contractors who worked at the building, we have a dispute with just one of them. That’s a good record.”